Embodiment in distributed information processing: "Solid" plants versus "liquid" ant colonies

Abstract

Information processing is an essential part of biology, enabling coordination of intra-organismal processes such as development, environmental adaptation and inter-organismal communication. Whilst in animals with specialised brain tissue a substantial amount of information processing occurs in a centralised manner, most biological computing is distributed across multiple entities, such as cells in a tissue, roots in a root system or ants in a colony. Physical context, called embodiment, also affects the nature of biological computing. While plants and ant colonies both perform distributed computing, in plants the units occupy fixed positions while individual ants move around. This distinction, solid versus liquid brain computing, shapes the nature of computations. Here we compare information processing in plants and ant colonies, highlighting how similarities and differences originate in, as well as make use of, the differences in embodiment. We end with a discussion on how this embodiment perspective may inform the debate on plant cognition.

Keywords: distributed computing; embodiment; information processes; liquid brains; solid brains.

Graphical abstract

Fig. 1.

Biological computing. All biological organisms, be it primates, snails, plants or single-celled amoebas, sense their environment and internal state, and process, integrate and prioritise this information to compute which action to take next. Figure inspired on earlier work in Scheres and van der Putten (2017).

Fig. 2.

Different spatial organisations of information processing in biological systems. Left: centralised information processing based on a central dominant brain in primates (Image source chimpanzees: https://sciencenorway.no, photographer Etsuko Nogami). Middle: hybrid information processing in an octopus that combines a central brain with semi-autonomous information processing in its arms. (Image source octopus: Octolab TV https://octolab.tv) Right: fully distributed information processing with no central processing organ in plants (Image source plant: New Jersey Agricultural Society Learning Through Gardening program) (Image computer: https://computerkiezen.nl/computer-soorten/desktop-computer/).

Fig. 3.

Storage of spatial environmental information. Top: in the solid brain setting of a plant root, environmental information regarding the direction of a salt gradient can be stored internally in the shape of an auxin asymmetry. Bottom: in the liquid brain setting of an ant colony, environmental information regarding the direction and shortest path towards a food source is stored externally through a pheromone trail.